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The Internet Was Wrong: Short Chainstays Suck*

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7/19/2016 10:04 AM

I think you need to consider a bike a whole, not just in terms of individual geometry dimensions. Everything needs to work together.

For example, a 26" full suspension bike with long stays may end up feeling similarly balanced to a 29er hardtail with short stays.

I agree that the shorter-is-better preference misses the big picture. But so does absolutely ruling out bikes with short stays.

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7/19/2016 10:10 AM
Edited Date/Time: 7/19/2016 10:34 AM

D(C) wrote:

I think you need to consider a bike a whole, not just in terms of individual geometry dimensions. Everything needs to work ...more

100%. Which is really what I'm trying to say. A bike needs to be well balanced to ride well.

The funny thing is what turned me onto this idea was in fact 29ers with "longer" (compared to my other bikes) stays. I was cornering better, riding faster and just generally having more fun - feeling more comfortable on the bike. I thought it was the bigger wheels, the head tube angle, the BB - until I rode a 27.5" bike with nearly ***identical*** geo numbers less the stays (and rear travel). Then it all came together when I put both bikes on the scales. Bar height, head tube, reach, stem, sweep etc were all the same. Chainstays were the only noteworthy difference.

So yeah, I never ever would have thought bigger wheels with longer stays would allow me to smash corners harder - but sure enough, in this particular case, it did.

But yeah, I'm not trying to say "make all bikes chainstays super long" - what I am saying is now that bikes have grown in front center, perhaps some bikes rear center needs to grow as well (or maybe just the larger sizes - or bikes intended for racing...)

Yes, I'm talking in circles.

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7/19/2016 10:59 AM

jeff.brines wrote:

The Internet Was Wrong: Short Chainstays Suck*

****Disclaimer - Full on bike geekery below - eyes *may* glaze over while ...more

Not sure if it would change your rationale but I'd be curious to know if both riders you mentioned are in fact on medium frames. I read somewhere that Troy was riding a large size specialized Enduro at that race. If I had to bet, I would say Rude rides a large...he was bigger than me when he was twelve. I ride a medium devinci dixon and always wanted to try the large. The medium is a fun park bike but a little twitchy and unstable at speed.

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7/19/2016 11:17 AM

Minnaar famously had a few breakout races on the now-legendary (yeah, I said it) XXL V10 (with ghastly long 17.75" stays).

How about 18.22 with the custom link!

Photo

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7/19/2016 11:24 AM

stflood wrote:

Not sure if it would change your rationale but I'd be curious to know if both riders you mentioned are in fact on medium ...more

I have a few sources indicating Richie was on a medium (like Graves used to be). Both are built like linebackers but aren't overly tall (5 10" or 5 11").

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7/19/2016 11:30 AM

What suprises me is that manufacturers claim their new bike is tweeked for optimum weight balance etc. But CS remains the same for all sizes which simply means the bigger the frame sizes the more weight is put on the back wheel. Where is the balance here? Maybe a fixed CS doesn't affect the weight balance much but still.

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7/19/2016 12:48 PM
Edited Date/Time: 7/19/2016 12:56 PM

T

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7/19/2016 12:48 PM

SJP wrote:

Hi Serge-W:

The OP started out with "The internet was wrong, short chainstays suck". Note the footnote associated with it: ...more

Hey! wow, didn't realize that @jeff.brines comment was considered rather rash. For me it was a bit of an exaggeration, but a funny one that was supposed to help drive home his point. But then again, that's just me, non-native speaker wink

yeah, I guess we were talking slightly past each other. I'm trying to look at single variables, so either CS or front center. In your case, your variable is the BB, aka the body anchor point at constant wheelbase. Fair enough. I would still maintain though, that a shift in BB location alters the weight balance of the bike. After all, isn't that what Minnaar did effectively on the XXL V10? I'm saying effectively, because of course they lengthened the bike altogether. But by first increasing reach, and then CS, and maybe going back and forth a bit, they were basically experimenting with different, relative BB locations.

But yeah, the body measurements must be the foundation to all this. It's astonishing how different the experiences are. And then there is the whole short bike is better movement in the 2000s, cramping Steve Peats and Greg Minnaars onto BMX bikes. Is anybody out there aware of any database regarding variability in human body measures?

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7/19/2016 12:58 PM

D(C) wrote:

I think you need to consider a bike a whole, not just in terms of individual geometry dimensions. Everything needs to work ...more

jeff.brines wrote:

100%. Which is really what I'm trying to say. A bike needs to be well balanced to ride well.

The funny thing is what turned ...more

So, you're recommending the Smuggler over the Patrol. Been curious on what your thoughts where.

To be fair, last 29' bike I had felt like the concept of changing directions was stupid and a sign of weakness. Needless to say, I don't own that bike anymore.

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7/19/2016 1:10 PM
Edited Date/Time: 7/19/2016 1:10 PM

Whattyabike wrote:

So, you're recommending the Smuggler over the Patrol. Been curious on what your thoughts where.

To be fair, last 29' bike I ...more

That's a tough call. For me, I know what I prefer 90% of the time. However, saying I recommend the Smug over the Patrol isn't totally accurate. If you are tall, trying to race and want an extremely versatile bike yes, I think its the call.

If you are shorter, maybe spend more time in a bike park or on fairly gnarly trails, maybe the Patrol is right.

Too many variables but without a question I'm more balanced, more comfortable and riding faster on the Smuggler than the Patrol.

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7/19/2016 2:05 PM

jeff.brines wrote:

100%. Which is really what I'm trying to say. A bike needs to be well balanced to ride well.

The funny thing is what turned ...more

Whattyabike wrote:

So, you're recommending the Smuggler over the Patrol. Been curious on what your thoughts where.

To be fair, last 29' bike I ...more

jeff.brines wrote:

That's a tough call. For me, I know what I prefer 90% of the time. However, saying I recommend the Smug over the Patrol isn't ...more

I'd be curious to see what your thoughts are regarding stem length too. I mean People rocking short CS with sub 50MM stems seems like it would naturally cause every bike to feel like they are on a wheelie machines. I'm thinking we've kinda ran with short stems and short CS for a bit too long and trying to make up the length in the wrong place.

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7/19/2016 2:13 PM

Whattyabike wrote:

I'd be curious to see what your thoughts are regarding stem length too. I mean People rocking short CS with sub 50MM stems ...more

I've played with a number of stem lengths. To be honest, it depends on your stack height (as your bars go up, your "effective" stem length goes down), reach, where you are riding etc.

I will say, in my experience, going north of 60 really isn't (ever) good. Unless you are andre the giant and running an uncut steerer tube wink

Usually, a stem around the length of the fork's offset is a good place to start (40-50mm)

J

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7/19/2016 4:08 PM
Edited Date/Time: 7/19/2016 4:09 PM

jeff.brines wrote:

I've played with a number of stem lengths. To be honest, it depends on your stack height (as your bars go up, your "effective" ...more

Had tried nearly exact of this idea last season. Was sicking up out of both ends day and night.

To correct all that, I'd used Fork Offset x 1.190476 to generate a stem length



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Shoes for Industry

7/19/2016 4:32 PM

What's with the controversial title, now that you've corrected the misunderstandings, misled by your original post? "Short chainstays suck" = Short chainstays aren't always better. Longer is better for taller riders, racers, and bikes with longer fronts?

You speak of balance, but balance can be found with short CS too. Compared to a Ripley, 17.4" CS, a Intense Spider 275c has a 16.5" CS and feels far more balanced and centered to me, both size med and me 5' 7". I found myself cornering from behind the saddle on the Ripley, while I'm centered 2-wheel-drifting on the Spider. I wasn't setting KOMs on the Spid, but it definitely was radder. Not too self-conscious about actual speed... the feel of going fast is pretty satisfying, even if it's not proved by the clock.

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7/19/2016 5:13 PM

FYI Rude does ride a medium (source: http://enduro-mtb.com/en/pro-bike-check-comparing-richie-rudes-cody-kelleys-yeti-sb6c/)

Interested to know the OP's views on bikes like the Ibis HD3 and Pivot M6? Both have short stays but also keep the reach sensible which should put the rider centred but between a shorter wheelbase than something like an SB6.

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7/19/2016 6:06 PM

Apples to apples I guess. Comparing a snowboard or ski to a bike in terms if balance is like comparing a bike to a motorcycle. Weight distribution in relation to the rider's mass is pretty different, as is the COG height.

Many people like long chainstays, and I bet the same amount swear by short ones. Count me in the second group. I'd trade stability for maneuverability any day. It all comes to your riding style. I like my bikes to turn over a dime, you might feel at home with a different geo.

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7/19/2016 6:17 PM

Specialized demo 8 and YT Tues .
Both at the top and both short chainstays

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7/19/2016 9:00 PM

i guess this thread only about gravity bike , AM & DH bike? how about other MTB like XC and trail bike? people say short CS is better on pedalling. does it counted as a positive value for a bike?

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7/19/2016 9:37 PM

jeff.brines wrote:

Few thoughts to add but before I do I should apologize for this coffee fueled rant. There were a few things I wasn't overly ...more

Buy a Norco... solved!

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7/20/2016 3:53 AM

utopiaarch wrote:

i guess this thread only about gravity bike , AM & DH bike? how about other MTB like XC and trail bike? people say short ...more

For XC and Trail-riding in general, a long CS means more grip while climbing. But you can't just throw a longer CS at an XC-bike because it adds leverage and you that needs to be taken into account when on the linkage design. I believe that the claim of shorter CS as a better pedalling platform comes from the fact that it puts your weight on the rear wheel so your pedal strokes don't put you deeper in the travel as easily as it would be if your weight was balanced. In our tests we've found out that longer bikes (long CS and long Reach with slack HA) beat shorter bikes that are considered "great at technical climbs" (because of their short CS), and they do that by a mile. On a longer bike climbing up your weight is at the correct position for the rear wheel to grip and if there are obstacles on the way up, a slacker HA makes it possible for the fork to absorb them and you don't get hung-up on square edges.

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7/20/2016 8:29 AM
Edited Date/Time: 7/20/2016 8:30 AM

stiingya wrote:

Buy a Norco... solved!

I do like Norco's method of changing the rear center for every size. However, I'd like to see more growth to keep everything in proportion as, in my opinion, the change isn't enough to make the difference I'd want to see.

So...here is the point to this half-baked rant. I've raced bikes for awhile in a number of disciplines. And yes, I ski. For both skiing and road bikes, there are a number of objective ways to determine mount point, ski length, shaping, stem length, frame size, seat position etc. For mountain bikes, we're still sort of using the "guess and check" method to determining what works and what doesn't. This makes some sense being the modern mountain bike rider is far more "dynamic" than that of the static (in one position more or less) road racer.

Put another way, if anyone has had a real road bike fit, you can attest to it being more of a science and less of an art. I'd like to bring this level of objectivity to mountain bike fit and geometry to get more riders on the best tool for the job. For a number of manufacturers, it really wouldn't matter as this level of customization is beyond their reach from a dollar and sense perspective. (though I still say growing the rear center slightly in the longer sizes will create a more balanced bike no matter what). That said, if you could better explain to a rider what sort of numbers to look for in a bike, you could steer them toward better buying decisions. As someone who has tested a lot of bikes, I can promise better fit/geometry will always trump better suspension. (as suspension can always be improved)

I've run formulas to try and figure out how much the rear center should grow in proportion to front center. As a number of people in this thread have noted, its different than skiing for the reason that there are two weighted points on the bike (handlbar and pedal). The proportion to how this is weighted is going to differ person to person and largely be determined by style, arm length, proportions etc. which is likely why some tall dudes may love short stays and some hate them (me).

If this bias between pedal/bar can be better quantified based of body proportions, perhaps we could arrive at a better fit system that goes more in line toward each rider getting on the right rig than simply following "internet trends"(low bars rule! short chainstays are the truth! Long bikes are the best! Slack HT angles rule! Stiff suspension is the best! etc)

Again, as I noted elsewhere in this thread, the ultimate would be some sort of group of sensors on the bike that could actively determine weight bias while riding and objectively explain what tweaks to geometry/suspension setup etc are doing to the the overall ability for the rider to stay in control.

I know, making a lot of leaps here. Its the internet. And this is a forum. Isn't this what its (internet forums) are for?

J

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7/21/2016 10:02 AM

Varaxis wrote:

What's with the controversial title, now that you've corrected the misunderstandings, misled by your original post? "Short ...more

With a revised title of "The internet was wrong: long chainstays don't suck", it would be quite accurate.

With a large helping of different body shapes and muscle densities, there is a lot of room for varying preferences. Add in just how big the differences are between terrain and the speeds people take it, there actually should be quite a decent range in preferred CSL.

Similarly playfulness has a few different meanings, and really depends on how people want to dick around on a bike, as well as the trail. For being able to quickly reposition on low speed technical stuff, and quickly modulate the pitch and yaw of the bike, shorter chainstays do carry advantages, particularly for less brawler-shaped riders. For others, being able to set a shock tune with minimal rebound damping to send hops off bonus lines without giving up stability in chunky stuff and being able to modulate weight balance in big drifty cornersis better, and to those riders a longer chainstay setup is going to be more playful. For riders that like both, it may be a terrain dependent preference.

As far as the weight distribution delta - a move of 0.6" of the bottom bracket on a fixed wheelbase is actually non-trivial. Considering that the axle to axle wheelbase of bikes is usually in the 46" range for a medium sized bike, with a chainstay length around 17", this puts a front center length at 29". Moving to half inch longer chainstays, and taking that out of the front center, it's about a 5% change in center of mass location between the two contact patches.

Also consider that in terms of a properly fitting bike with properly located rider that the pedal axle to ankle location is going to be ideally constant (especially when going downhill), therefore the bottom bracket sets the location of the rider's lower body. When in attack position, the only other contact points are the grips, and consequently moving those forward to achieve proper fit is going to move the rider either farther forward also, or rely on adding some stack to keep the overall pythagorean reach-stack sizing the correct size for the rider (basically rolling the rider back @ the hip to get the same fit happening). Especially when adding inclines, the ramifications for these changes on weight distribution at the contact patches are significant.

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7/21/2016 10:27 AM

I think the chain stay balance issue is just a part of the bigger need to scale bikes proportionately..... There seem to be 2 key areas (1) proportionate chainstays and (2) stack to reach ratio.

As far as I know there isn't a manufacturer who broadly maintains stack to reach ratio across sizes. I know for some very small sizes it's hard not to have an extreme high stack relative to reach but in general it's the L/XL/XXL that have the problem of very low stacks that riser bars can't cure.

That means that there's almost no point in asking a tall dude and medium sized dude to compare thoughts because the tall dude already has his weight forward due to the lower relative stack.

People talk about keeping the weight on the front wheel.... I've never had this problem! I wonder what it's like?

JUST on CS.....
I've had bikes with CS ranging from 415 to 450mm (including one with 15mm of adjustable CS) and I've tried a 455 bike. There is no doubt that balanced CS is important and my hats off to Norco for trying to produce what felt like a balanced bike. The adjustable CS was a real eye opener and I agree it's a great idea for letting a tuner ride a bike to their riding needs and size.

Proprotionate CS aren't just needed for balance and high speed but also for climbing if your tall. A steep post is only part of the solution to this issue. I did a bunch of calculations and the balance angle (when the seat is over the rear axle for arguments sake) varied massively for so called All mountain bikes for large sizes. The range was 10 to 17 degrees and I'm sure I didn't find the lowest!

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7/22/2016 5:53 AM

Some of you guys probably would enjoy playing around with an EBB.

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7/27/2016 7:19 AM
Edited Date/Time: 7/28/2016 1:08 AM

And what do you guys think about chainstay length and body position on a hardtail.
I mean, you ride a unsuspended bike differently, right?
More laid-back, less aggressive?
Would love to hear some thoughts about it.

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8/3/2016 4:23 AM

"Richie Rude: SB 6c medium - 17.4" chainstays
Sam Hill: NukeProof Mega (guessing a medium) 17.5" chainstays"

... I guess this argument is now moot

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8/3/2016 4:36 AM

creg wrote:

"Richie Rude: SB 6c medium - 17.4" chainstays
Sam Hill: NukeProof Mega (guessing a medium) 17.5" chainstays"

... I guess this ...more

You could sum it up as "I want everyone to run the same setup I do in order to feel reassured in my elections!"

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8/3/2016 5:10 AM

Thomsen wrote:

And what do you guys think about chainstay length and body position on a hardtail.
I mean, you ride a unsuspended bike ...more

Not read anything else in the thread, was kind of skimming through to see if anybody mentioned hardtails.

I bought a Kona Explosif with adjustable dropouts earlier this year and despite the fact i dont believe shorter=better, i slammed them to the front (425mm). I ride techy, steep, rough trails and this definitely gave the bike a skittish character, felt very reliant on the forks doing their job and letting the rear end bounce around and hopefully follow suit.

After sliding the dropouts back (445mm) i feel a lot more comfortable descending in terms of position and weight distribution on the bike, also, being a hardtail, increasing CS length gives a little more flex and therefore more small bump compliance.

My opinion is that whether HT or FS, the CS length should be proportional to the reach in order to give a balanced riding position, riding with a higher weight distribution over the either wheel is not as efficient as riding with even weight distribution.

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8/3/2016 6:14 AM

responsiblepirate wrote:

Not read anything else in the thread, was kind of skimming through to see if anybody mentioned hardtails.

I bought a Kona ...more

That last bit is what I'm getting at. 16.x" stays on a small probably feels great! 17.9" on an XL probably feels pretty semi-truck ish and, well, shit.

I'm not saying we need the longest stays on every bike to go fast, but I am saying when looking at the application and overall bike size, going longer in a number of cases really would help the bike work better under the rider.

Alternatively, everyone can go get two scales and check your weight distribution in your neutral position. Stack, head angle, reach, bar sweep, stem, fork pressure, rear shock pressure, tokens etc all play into this but this is number I'm driving toward equalizing. Regardless of the characteristics short/long stays might bring forth, getting the weight distribution nearly 50/50 (with a trail bike) while keeping stem length close to fork offset, reach numbers around 18.5-19 and head angle between 67-66 (29" application) is what I'm after first and foremost. Wish we could bring back adjustable stays for this very reason...

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8/3/2016 8:06 AM
Edited Date/Time: 8/3/2016 8:07 AM

jeff.brines wrote:

That last bit is what I'm getting at. 16.x" stays on a small probably feels great! 17.9" on an XL probably feels pretty ...more

exactly, its all about proportion, CS should increase with reach.

How well would a human work if the legs never grew proportionally with torso length?

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